Shell grommet



Dec. 25, 1945. w. J. FRIDERICI SHELL GROMMET Filed Jan. 27, 1941 INVENTOR m m m R Mdm mm A IY WLB M Patented Dec. 25, 1945 Nitti 'args SHELL GROIVIMET Application January 27, 1941, Serial No. 376,167

4 Claims.

The invention relates to a rifling band protector, sometimes known as a grommet. It is particularly useful in connection with the handling of ordnance shells of conventional cylindro-conical contour which are handled or stacked in a manner involving continued or occasional undesired contact with each other or with surrounding objects.

As is Well known to those skilled in this particular art, most projectiles are fired from rifled gun barrels.` The service life of a gun depends on the condition of the rifling grooves therein. The shells are usually provided with a band of soft metal` such as copper, superimposed on the shells exterior periphery at a suitable point, which soft metal band bears against and Within the grooves as the shell is fired. The use of a soft metal band to seize in the gun rifling and impart a rotary motion to the projectile is well known to ordnance experts.

When projectiles are being handled, piled, or shipped after nal assembly, they may be subjected to unavoidable rough handling, andl sometimes, When in actual use in the field, they must be transported for considerable distances over rough roads or irregular terrain, by truck or in any other possible manner. The effect of stacking, rough handling, or jolting becomes immediately apparent upon the soft metal band which, obviously, must protrude circumferentially beyond the balance of the cylindrical periphery of the shell. The accuracy and efciency of gunfire depends on the maintenance of accurate dimensions in the riing band.

It is an important object of my invention, therefore, to provide an improved means for protecting the rifling band of shells while they are being handled, stacked, or shipped or in any way dealt with prior to loading.

It is a further object to provide a grommet having fastening means whereby its ends may be readily connected and disconnected without the use of special tools, to thereby enable the grommet to be easily, quickly and `conveniently applied to and removed from a shell.

It is a further object to provide a grommet having fastening means including a readily frangible or bendable tab struck up from a metal part of the grommet, to thereby effect the release of the tie wire of the fastening means and thus effect the release of the grommet from a shell.

It is a further object to provide a grommet which is especially suitable for use with a shell, the rifling band of which has an external surface of generally convex form with substantially no side edge abutments.

Further objects and attendant advantages will be apparent on consideration of the following description and the drawing attached herewith illustrating a preferred embodiment.

Fig. 1 shows a conventional projectile carrying a riing band and having a grommet placed thereon.

Fig. 2 `is a section taken on the line 2-2 of Fig. 1.

Fig. 3 isa greatly enlarged portion of a part of the section shown in Fig. 2, to more clearly illustrate the attaching means, and the method of disengaging it. Fig. 4'is a top plan view of a grommet blank, before application to a projectile.

Fig. 5 is a section taken on the line 5 5 of Fig. 4.

Fig. 6 is a section taken on the line 6-6 of Fig. 4.

Fig. l is a section taken on the line 'l-l of Fig. 4.

Fig. 8 is a transverse section of another grommet embodying my invention.

The grommet shown in Figs. 1 to '7 is specifically devised for application to rifling bands, the lateral edges of which do not project to any substantial extent beyond the cylindrical contour of the shell. It is particularly adapted to rifling bands of this nature which are slightly convexed, or which taper both directions from their circumferential mid-section, as indicated in dotted lines in Fig. 7. Such a rifling band is used, for example, on substantial quantities of projectiles used by Great Britain in the present war.

In the manufacture of mypreferred form of grommet, I first procure a metallic backbone strip I0 of sheet metal which may be provided with staggered apertures llas indicated by dotted circles in Fig. 4, to provide a keying or anchoring effect for a coating as will soon appear. The metal stock should be malleable enough to suitably respond to bending and forming operations Vand may preferably be galvanized or otherwise coated to protect it against any corrosive effect. A variety of suitable metals and alloys can be suggested by those skilled in the metallurgical arts.

A coating or jacket of soft material I2, for instance rubber, or rubberlike material, plastic, textiles, synthetic resins, pulps, or in general any one of a number of plastic materials is now applied to the backbone member, preferably by a familiar extrusion process. In the perforated form of backbone Vhere illustrated the plastic material ows through the perforations II and forms an interlocked or anchored bond. In the device shown the metal is completely enclosed, but it is quite feasible to coat one face only of the grommet since this affords substantial protection, as

will appear.

A facing sheath I3 of nonadhesive material, such as cotton fabric, is preferably placed upon the coated strip completely shielding one face and both lateral edges and running over a portion of the other face. If applied while the coat-V now cut into suitable 1engths,sufcient to encomc pass the periphery of the rifling band which it is intended to protect. Slightly upturned tabs Id and I5 are struck up from the material of the strip near its respective ends, for instance by a punch-pressing operation. Tab I4 may be of any simple contour adequate to retainthereunder a wire tie member IS. VTab I5, however, is especially formed and adapted for its subsequent function and it will now be more fully described. As shown particularly in Figs. 3 and 6 it is formed with a central longitudinal beaded portion I 1, embossed or indented thereon during the punching operation. This bead extends from its tip end I8 to a location adjacent its base at the line of departure of the tab 4from the grommet strip. The purpose of the bead is to strengthen the upturned portion of the tab, and to locate the natural bend line of the tab along a line adjacent said grommet strip, where said bead terminates, and other suitable strengthening means may be used, if more convenient or desirable.

A transverse tunneled portion I9 may be provided ,in the neighborhood of the bending line to form a natural seat for tie wire I6, as best shown` around a projectile until the ends approach an e abutting relationship. A length of tie wire I6 provided with suitable manipulating loops 20 at its ends, is inserted under both tabs, and the loose ends of the wire are then twisted, for instance by inserting any convenient small object through the loops and imparting rotary motion thereto. As a result, the grommet ends are drawn together until the grommet seats in tight fitting relationship on the riing band. 'Ihe resilient coating I2 assists in promoting an even seat and a good fit, and the nonadhesive material I3 prevents the plastic material i2 from sticking on the riflng band after the grommet is removed. YThe somewhat enlarged bead portions 2| along the lateral edges of the grommet are predetermined in shape and size by the circumferential contour along the junction of the projectile and rifling band, and these beads may be entirely eliminated in some adaptations. Centrally located circumferential beads might be provided to seat in corresponding grooves or to straddle corresponding ridges in other designs of rifiing band.

Fig. 8 is a transverse section of another grommet embodying my invention. As may be seen from an examination of Fig. 8, the backbone strip 22 is encased in resilient material 23 and carries a facing of nonadhesive material 24. The lateral edges of the backbone strip carry a succession of slots 25, one being shown, so as to provide serrations which may be bent inwardly and then back upon themselves to form a strengthening fiange 2E. The strip 22 may further be provided with a succession of slots 2l, one being shown in Fig. 8, to facilitate the formation of a longitudinal ridge 28 such as mentioned in the preceding paragraph. Y

In manipulating a gun on a warship or in the eld, under frequently adverse temperature conditions or otherunfavorable attendant circumstances, it is most desirable that the grommet be removable with celerity and ease, and without recourse to special tools. With the type of grommet here shown the finger may be inserted under thevtip I8 of the tab I 5, and the tab thereby turned upwardly and backwardly as indicated by the dotted lines in Fig. 3. As hereinabove described, the tab bends re'adily along a predetermined line as controlled by the positioning of bead I'l. As is immediately obvious, the tab may be bent to an angle which will permit the tie wire to be slipped olf, thereby releasing the grommet from the rifling band. If desiredY the bending zone of the tab may be reduced in section in the forming operation so as to beY readily frangible since the grommet is manufactured so cheaply that no attempt is made to recover it.

It is now apparent that by providingV a tab of specific design adapted to a grommet of suitable contour, it is possible to apply a Protective shield to a rifling band and remove it therefrom with minimum time and trouble, while nevertheless assuring a secure nt during shipment or handling of the projectile. My device and manner of applying and removing the same, in any useful adaptation or equivalent thereof, are comprehended within the scope of the claims appended herewith, it being understood that the terminology or phraseology herein employed is for the purpose of description and not of limitation.

Obviously the device will function successfully if only one tab is used, the tie means being aixed in any suitable way to the metal reinforcing strip at the opposite end of the grommet. It is further apparent that while a beaded 0r embossed portion operates very successfully in reinforcing the tab, other reinforcing means may be utilized without departing from the scope of the invention as delineated in the appended claims,

What I claim is:

i. Tie means for a riing band protective grommet of the type wherein the grommet has a metal supporting strip, and a relatively soft, nonmetallic covering layer c-arried on said supporting strip, and wherein said tie means is adapted to retain said grommet in encircling relationship on said rifling band, said tie means comprising loop means connected with one end portion of said strip, the other end portion of said strip having a tab integral therewith, said tab having a free end portion lextending outwardly at an angle from said strip to provide an entrance thereunder for said loop means, and said tab being provided, immediately adjacent its connection to said strip, with a tunneled recess to receive the free end of said loop means, said tab having a reinforced portion and a non-reinforced portion, said non-reinforced portion being adjacent said tunneled recess, said tab being readily bendable at the nonreinforced portion to release said tie means, and

hence permit said grommet to be readily removed from said riiiing band.

2. Tie means for a rifling band protective grommet of the type wherein the grommet has a metal supporting strip, and a relatively soft, nonmetallic covering layer carried on said supporting strip, and wherein said tie means is adapted to retain said grommet in encircling relationship on said rifling band, said tie means comprising a pair of tabs struck up from the abutting ends of said metal strip, one tab adjacent to but spaced from each end of said strip, connecting loop means having a portion thereof retained by each said tab for maintaining said strip ends in sub stantially abutting relationship, one of said tabs being provided, in the region of its connection respectively retained portion of said loop means, said last named tab having a strengthening bead along a substantial portion of its length, and having at the inner terminal portion of said bead, in the neighborhood of said tunneled recess, a relatively more bendable zone, whereat said last named tab may be readily bent backwardly to release said tie means and hence effect quick removal of a grommet from said riing band.

3. A grommet for encircling a shell for the protection thereof, said grommet having tie means adjacent one end, and a tab integral with the e to said strip, with artunneled recess to receive its Y Y grommet and located adjacent its other end, said tab having a tunneled recess for the releasable retention of said tie means, whereby said grommet is releasably retained around said shell, said tab having a reinforced portion and a nonreinforced portion, said tab being readily bendable at the nonreinforced portion adjacent the area of juncture between said tab and said grommet to facilitate release of said tie means, and hence permit said grommet to be readily removed from the shell.

4. A grommet for encircling a shell for the protection thereof, said grommet having tie means adjacent one end, and a tab integral with the grommet and located adjacent its other end, said tab having a ared-up portion at its tip and for the convenient ninsertion and subsequentiirelease of said tie means, and said tab having a tunneled recess for the releasable retention thereunder of said tie means, whereby said grommet is releasably retained around said shell, said tab having a reinforced portion and a nonreinforced portion, said tab being readily bendable at the nonreinforced portion adjacent the area of juncture between said tab and said grommet to release said tie means, and hence permit said grommet to be readily removed from the shell.

WAYNE J FRIDERICI. 

